Lubricant and hydraulic fluid compositions



Patented Apr. 28, 1953 LUBRICANT AND HYDRAULIC FLUID COMPOSITIONSForrest J. Watson, Berkeley, Calif., assignor to Shell DevelopmentCompany, San Francisco, Calif., a corporation of Delaware No Drawing.Application June 9, 1950, Serial No. 167,262

20 Claims. 1

For example, it is important that hydraulic fluids do not corrode themetal surfaces with which they come in contact. It is also importantthat hydraulic fluids are not subject to and resist.

deteriorationdue to oxidation. The ability of a hydraulic fluid toresist oxidation is closely related to its corrosivity to metal surfacessince,

in general, the oxidation products are extremely corrosive to metalsurfaces. Because of the highly machined metal surfaces and closetolerances found in hydraulic mechanisms, any tendency of hydraulicfluids to destroy the same, as by the combined action of oxidation andcorrosion, is highly objectionable and should be obviated.

Other desirable properties for hydraulic fluids, particularly for use inaircraft hydraulic mechanisms, are fluidity over a wide range oftemperatures, at least as low as about -l0 F. to about 60 F.,lowvolatility at a temperature at, least as high as200 F. orhigher andnonflammability.

Hydrocarbon oils, such as mineral lubricating oils and the like,synthetic lubricants, such as alkyl esters of organic acids andpolymerized alkylene oxides, and compositions containing the same havebeen employed as hydraulic fluids. However, these compositions aresubstantially flammable and their use as hydraulic fluid in 2 acid aresubstantially non-flammable and possess many other Properties which maketheir use in hydraulic fluid compositions for aircraft desirable.Organic phosphates, such as the above esters, like most phosphoruscontaining organic compounds, are, however, corrosive and/or susceptibleto oxidation and therefore there is at least some reluctance to the useof these materials in aircraft hydraulic systems.

It is, therefore, an object of this invention to provide stable,non-corrosive compositions, especially liquid compositions suitable foruse as lubricants and in hydraulic mechanisms, particularly in aircrafthydraulic mechanisms. It is another object of the present invention toprovide improved stable, non-corrosive compositions containing orcomprising an organic phosphorus-containing compound. These and otherobjects will become apparent from the description of the invention setforth hereinbelow.

Now, in accordance with the present invention, it has been found thatthe above and other objects may be attained by a composition comprisinga base lubricant and minor amounts of two particular types of additives,the combination of which exerts an unexpected and synergistic effectupon the base lubricant resulting in a composition of outstandingstability and non-corrosivity. More specifically, it has been found thatphosphorus-containing compositions, especially organicphosphate-containing compositions, which contain minor amounts of anepoxy compound and an organic sulfur-containing compound, preferably anon-oXygen-containing organic sulfur compound, are substantiallynon-corrosive and oxidation stable.

The organic phosphorus-containing compositions which are so effectivelystabilized by the combination of additives of the invention includecompositions which contain or comprise the. following organicphosphorus-containing compounds in major or minor amounts: the trialkylphosphates, especially the trialkyl phos- .phates wherein each of thealkyl groups contain from 4to 9 carbon atoms such as tributyl phosphate,dibutyl octyl phosphate, triamyl phosphate, tri-2-ethylbutyl phosphate,tri-n-hexyl phosphate, tri-2-ethylhexyl phosphate, tri-noctyl phosphate,tris(3,5,5-trimethylhexyl) phosphate, tri-n-nonyl phosphate, and theirhigher molecular weight homologs; the triaryl phosphates, such as thetricresyl phosphates, diphenyl cresyl phosphate; halogen substitutedtriaryl phosphates, such as diphenyl o-chlorophenyl phosphate; mixedalkyl aryl phosphates, such as diphenyl octyl phosphate, diphenyl ethylphosphate; and the trialkaryl phosphates which may also be considered tobe triaryl phosphates such as the trixylyl phosphates and thetripseudocumyl phosphates. Other phosphoruscontaining compositions towhich the invention is applicable include compositions which comprise orcontain a trialkyl phosphite, such as tributyl phosphite; an aliphaticphosphonate, such as an alkyl alkenyl phosphonate, e. g., dioctylisooctene phosphonate; an alkyl phosphonate such as di-n-butyl n-octanephosphate; a mixed alkyl aryl phosphonate, for example an alkyl aromaticphosphonate such as dioctyl styrene phosphonate; an aliphatic phosphate,such as tri-2-chloroethyl phosphate, the phosphate of 3-hydroxy-propylamyl sulfide; tributoxyethyl phosphate and tri-butoxyoctyl phosphate; analkyl alkane phosphonate,v especially the dialkyl alkane phosphonate,such as dibutyl n-octane phosphonate and dimethyl tetradecanephosphonate; a trialicyclic phosphate such as tris(trimethyl cyclohexylcarbinyl) phosphate; an alkyl alkane aromatic phosphinate such as butylbenzene-butane phosphinate; an alkyl dialkane phosphinate such as butyldibutane phosphinate; an alkyl aromatic aliphatic phosphinate such asbutyl benzene methoxymethane phosphinate; the organic phosphine oxides,such as the trialkyl phosphine oxides and the triaryl phosphine oxides;the various phosphono compounds, such as the bis- (dialkyl phosphono)alkanes, e. g., bis(di-nbutyl phosphono) 1,6-hexaneand bis(di-nbutylphosphono) 1,4 butane; the various tris (dialkyl phosphono) alkylphosphates, e. g., tris fi(di-n-butyl phosphono) ethyl phosphate. Ingeneral the phosphorus-containing compounds which are effectivelystabilized by the combination of additives of the invention includethose compounds containing all and only the following atoms, namelycarbon, hydrogen, oxygen and phosphorus atoms.

The phosphorus-containing compositions may contain one or more of theabove'compounds and classes of compounds. Thus, mixtures of trialkylphosphates and/or triaryl phosphates may be present. Furthermore, asingle phosphorus-containing compound, such as the trialkyl phosphatesand triaryl phosphates may contain the same or similar substituentgroups (alkyl, aryl, alkaryl) in all three positions or may possess amixture of various substituent groups.

The combination of additives comprising the present invention isespecially effective in reducing the corrosivity and oxidationsusceptibility of compositions containing an organic phosphate, atrialkyl phosphate, and/or a triaryl phosphate, and/or a mixed alkylaryl phosphate or mixtures of the same as well as the correspondingphosphonates and phosphinates.

The combination of additives of the subject invention has also beenfound to be an effective corrosion and oxidation inhibitor in many typesof lubricating compositions and hydraulic fluids,

such as synthetic lubricating oil compositions and mixtures thereof. Thecombinations of additives are however especially effective inlubricating and/or hydraulic fluid compositions which contain aphosphorus-containing compound, especially compositions containing anorganic phosphorus-containing compound as the predominating and majorcomponent, i. e., those compositions where the proportion ofphosphorus-contaming component(s) is greater than 50% by weight of thetotal composition. However, effective results are also obtained by thesubject combination of additives wherein the proportion of organicphosphorus-containing compound(s) is less than 50% of the totalcomposition but greater than the proportion of any other specificcompound therein.

In practice the proportion of organic phosphorus-containing compound(s)present in compositions of the invention may be between 50% and to byweight of the total composition, although usually the proportion isbetween 65% and 85% by weight of the total composition.

One of the additives of the present invention is an organic compoundwhich contains an epoxy group, i. e., an organic compound containing anoxygen atom which is linked with two different carbon atoms alreadyconnected in some other way. Preferred groups of epoxy compoundssuitable for the purposes of the invention include: aryl epoxy compoundssuch as pinene oxide and styrene oxide, glycidyl ethers, particularlyglycidyl ethers containing one carbocyclic group directly attached tothe ether oxygen atom, such as glycidyl phenyl ether. Specific epoxycompounds among the glycidyl ethers which are applicable in compositionsof the invention include glycidyl cyclohexyl ether and glycidyl o-cresylether. Other epoxy compounds among the glycidyl ethers which may beemployed include the alkyl glycidyl ethers, such as glycidyl methylether, glycidyl ethyl ether, glycidyl isopropyl ether and their highermolecular weight homologs. Epoxy compounds of the type represented bythe olefinic oxides, such as isobutylene oxide,

ethylene oxide, propylene oxide, isoprene oxide,

decene oxide and butadiene monoxide are also suitable. Other suitableepoxy compounds include the aliphatic epoxides, such as epichlorohydrin,glycide, chloroprene oxide as well as the alicyclic epoxides, such ascyclohexylene oxide and cyclopentene oxide;

The epoxy compound which is one of the two components of the combinationof additives of the invention may be present in compositions of theinvention, such as in compositions containing an organicphosphorus-containing compound, in an amount between about 0.25% toabout 5% by weight of the total composition. Particularly effectiveresults are obtained in said compositions wherein the epoxy compound,such as a glycidyl aryl ether or a glycidyl alkyl ether or an arylepoxide is present between about 1% to about 2% by weight of the totalcomposition.

The other ingredient of the combination of additives employed in thesubject invention is an organic, preferably oil-soluble,sulfur-containing compound, such as an' organic sulfide and/or anorganic disulfide. Preferred groups of organic sulfides suitable for thepurposes of the invention include the following hydrocarbyl sulfides;the aliphatic disulfides, especially the high molecular weight alkyldisulfides containing from at least about 8 carbon atom'sto about 20carbon atoms in the aixyl group present therein, such as dioctyldisulfide, dinonyl disulfide, dilauryl disulfide, distearyl disulfideand diheptadecyl disulfide; the aryl disulfides, such as dibenzyldisulfide, diphenyl disulfide, dixylyl disulfide and dinaphthyldisulfide. Other preferred organic sulfides include mixed disulfides,such'as the alkylaryl disulfides, sulfurized olefins, sulfurizedterpenes as obtained by the reaction of a terpene, such as pinene, withphosphorus pentasulflde, paraffin wax disulfide, such as obtained by theBlanksma reaction by treating chlorinated paraffin wax with sodiumdisulfide and sulfurized animal oils, such as sulfurized sperm oil.

The organic sulfide most preferred in the combination of additives ofthe invention is a wax disulfide, which may be obtained as a reactionproduct of sodium disulfide and a chlorinated paraffin wax, and may beprepared in the following manner: Approximately 5.5. parts by weightsodium disulfide is dissolved in about 2.2 parts by weight of water; thesolution is heated and about .7 part by weight sulfur dissolved thereinwith stirring. The resulting solution together with about 5.2 parts byweight of a chlorinated paraffin wax (chlorine content approximately 30%by weight) and about parts by weight each of denatured alcohol andnaphtha were charged into an autoclave and stirred therein at atemperature of about 145150 C. for 10 hours The maximum pressuredeveloped was about 220-230 p. s. i. After cooling, about 10 parts byweight water was added and thoroughly admixed. Two layers separated uponstanding, a naphtha layer and an aqueous layer. The naphtha layer wasseparated, dried over anhydrous sodium sulfate, filtered and the naphthadistilled off under reduced pressure, the maximum kettle temperaturebeing not greater than 140 C. There was obtained 21.6 parts by weight ofproduct (wax disulfide) as a viscous, oil-soluble, dark-colored liquid.

A typical analysis of a wax disulfide employed in the compositions ofthe invention is set forth below:

Specific gravity 20 C./4 C 1.024 Molecular weight 1 1050 Sulfur per centby weight 20-23 Chlorine do 1.5

Among the sulfurized olefins found; to be especially useful are, forexample, sulfuri zed paraflin wax (as may be produced by chlorination ofparaflin wax having an average molecular weight between about 225 and975, dehydrochlorination of the chlorinated product to produce waxolefins and sulfurization of the latter) sulfurized olefin or diolefinpolymers boiling above about 400 C., such as are obtained as by-productin the refining of cracked distillates with clay or other refiningagents, or in the polymerization of normally gaseous olefins to producegasoline or the like (e. g., sulfurized methyl pentadiene polymer).Sulfurized esters of unsaturated fatty acids with monohydric alcohols,as methyl, ethyl, propyl, etc.; sulfurized spern oil; sulfurized jojobaoil, are also useful sulfur-containing compounds which may be employedin the compositions of the invention.

The other component of the combination of additives of the invention, i.e., the organic sulfurcontaining compound, such as an organic sulfide(the sulfur-containing component of the combination of additives) may bepresent in amounts between about 0.025 to 1 or 2% by weight of the totalcomposition; 'Efiective :results are usually obtained when thesulfur-containing component of the combination of additives is presentbetween about 0.05 and between about 0.2% by weight of the totalcomposition. Typical examples of the sulfur-containing component as setforth hereinbefore include such organic sulfides as the alkyldisulfides, the aryl disulfides, wax disulfide, sulfurized sperm oil,sulfurized olefin, especially the sulfurized wax 'olefins.

The combination of additives of the present invention is usually presentin phosphoruscontaining compositions in an amount between about 0.5 andabout 6% by weight of the total composition. Mixtures of various epoxyand sulfur-containing organic compounds may be employed in thecompositions of the invention.

Compositions possessing lubricating properties, especially hydraulicfluids, usually contain viscosity index-improving agents, such as apolyisobutene, polymerized organic silicones,'polymerized styrene andvinyl compounds, such as an alkylated styrene polymer, etc. Typicalisobutene and alkylated styrene polymers which may be used as aviscosity index improvre have the following physical properties:

1 Saybolt Universal viscbsity.

In general the above viscosity index improving agents have an averagemolecular weight of from about 5,000 to about 35,000. Viscosity indeximproving agents which may b used in the compositions of the subjectinvention, also include polymerized esters of the acrylic acid series,such as polymerized acrylic acid estersand more particularly polymerizedmethacrylic acid esters. The latter are readily available as commercialproducts, and are sold under the trade-name Acryloid. The esters to beused should have molecular weights from about 5,000 to about 25,000preferably 5,000 to 15,000. It is understood that this is an averagefigure for the mixtures of polymers which is usually present due to thegreater or lessor degree of polymerization.

The acids should preferably be esterified with aliphatic alcohols havingtwo to fifteen carbon atoms, and the polymers may be homopolymers of asingle ester or may be copolymers of a mixture of suchesters. The termpolymerized esters will be understood to include both of these types.

The polymerized esters are generally available as concentrateddispersions in a solvent, such as a light mineral oil. The commerciallyavailable varieties usually conatin about equal amounts of the polymerand the solvent. Typical Acryloid viscosity index improving agents areAcryloid HF 855 and Acryloid HF 8125. Acryloid HF 855 is a solution ofthe polymerized ester in a petroleum base stock of a 200 F. flash pointmineral oil and a 30% by weight solution has a viscosity of 55centistokes (cs.) at 210 F. in a standard base stock having a viscosityof 3.3 cs. at F. Acryloid HF 8125 is a solution of the polymerized esterinfa petroleum base stock of a 300 F. flash point ass a, 8.62

7 mineral oil and 1a 30% by weight solution has a viscosity of 125 cs.at 210 F. in a standard base stock having a viscosity of 3.3 cs. at 100F.

The viscosity index improving agents may be present .up to about 10% byweight of the composition, also chlorinated hydrocarbons.

The following examples illustrate the present invention.

present in effective minor amounts up to about 20 25% by weight of thetotal composition. Gen- Elm-1E I erally, these agents may be employed inan To demonstrate the remarkably reduced .coramount between about 2% toabout by rosivity and oxidation susceptibility of phosweight, preferablybetween 5% and 10% by phorus-containing compositions wherein thecomweight. However, lower or higherconcentrations 10 bination ofadditives according to the present may, if necessary or desirable, beused. invention is present and in order'to demonstrate While theabove-indicated combination of-adthe synergistic action of thecomponents of the ditives has been found to be the most effectivecombination of additives according to the present as corrosion andoxidation inhibitor, other corroinvention, various phosphorus-containingcomposion inhibitors may in addition be present. Other itions weresubjected to the oxidation and corroinhibitors which may be present aswell include sion testdescrioed in Army-Navy periodicalspechydroxyaromatic carboxylic'acids, 'alkyl malonic ification forhydraulic oils, AN-0-366, June 1947. acids, the polyvalent metal saltsof hydrocarbon After one week at 121 C. as prescribed for the sulfonicacids, amines, amino phenols and the above-identified test the followingresults set other substituted phenols. forth in Table A belowwere'obtained.

Table A Corrosion-Weight loss, rug/cm Oxidation No Composition-Allpercentages are Percent percent by wt. Acid Increase .Cu Mg Fe Cd A1Neut. in Vise.

No. at

[g9 %lilfihel1l0t3fl1gh0$llll 8.50 0.01 0.02 0.06 0.01 2.

1p eny 00 y I) OSpltl 0 u%"glcyciqylphenylether 4.13 0.01 0.02 0.09 0.011.63 f gfvv a c l is l li e j .{Ti, 0.63 0. 01 0,04 0. 03 0. 02' 2.31

98.9% diphenyl octyl phosphate 4 1%glyc1dyl phenylethcruu. 0. 40 0. 010.02 0.02 0.02 1.14

0.1; vtvax dislulhlqdegn 5 100 riocty p osp etc. 7.91 7.02 0 3.17 0.02

triocltyll pklliospiiaten. 37 l 56 6 .3 gyci y p eny other. 0.28 0. 01 00.05 0.

t 0.1% wax disulfide. O1 0 25 2 5 84% triofityl phosphate 1 itfifiytiitiiifi ffiiifiiz::::::} +0.07 41 gly idyl phenyl ether.

0.28 0.01 0.1 0.2 0.9%g1ycidyl phenyl ether. 0 V O 0 0 2D 4 0.1% Waxdisulfide" 83.5% trioctyl phosphate. 9 $9.0 ,;ggigg g s ggfi; 4. 04 0.07 0 2. 01 0. 01 17.7 26

1% glycidyl phenyl ether 83.5% triootyl phosphate. 10% t1 icresylphosphate 10 5.5% Acryloid 111 855.. 1.04 0 0.01 0. 02 0.01 0.33 5

v 1.9% glycidyl phenylet 3.1% wax disulfide 11 100? bis(2 -3thylhe. ny

p lne 0X1 e 45.3 0.08 0.08 0. 04% bisCZ-ethylhexyl) phony] 08 +0 08 19 7so 5 if i fi sfai 12 o .cryoio 1.88 0 0.

0.0 glycidylpheny1ether 08 +0 20 O O 6'; 6 0.1% wax disulfidc Thephosphorus-containin compositions of the subject invention may bemodified by and include other suitabl ingredients, preferably in ininoramounts. Such optional ingredients include mineral oils, synthetic oils,and flame-proofing compounds.

Suitable synthetic lubricants which may be present in thephosphorus-containing composition of the invention include especiallythe polymerized .alkylene oxides or glycols, such as polymericl-2-propylene oxide and polymerized trimethylene oxide. Another'type ofsynthetic lubricant which may be present includes esters of dicarboxylicacids such as the sebacates and adipates as well as other acids havingfour to twelve carbon atoms, said acids being esterified with alcoholshaving two .to fifteen carbon atoms, such as di(2-ethylhexyl sebacate.

Flame-proofing agents which may be present are-exemplified by methylene.iodideand maybe The above data effectively demonstrate the superiorityof organic phosphorus compositions containing the combination ofadditives of the invention relative to freedom from corrosive attack.upon metal and oxidation susceptibility.

EXAMPLE II Table B The following table illustrates specific compo-Oorrosion-Weight loss, mg/cm Oxidation Composition-A11 percentages arepercent by wt.

Acid Neut. No.

Percent 1ncrease 1n V180.

at 100 F.

100% trioctyl phosphate 0.1% wax sulfid 98.9% trioctyl phosph 1%glycidyl o-cresyl ether 0.1% wax disu1fide...- 98.9% trioctyl phosphat1% styrene oxide.. 0.1% wax disulflde... 98.9% trioctyl phosph. 1%styrene oxide 0.1% di-benzyl disu1fide. 98.95% trioctyl phosphate.- 1%glycidyl phenyl ether 0.05% di-butyl disulfide. 98.9% trioctylphosphate. 1% glycidyl phenyl ether 0.1% di-Benzy1 disulfide.. 84%trioctyl phosphate 10% diphenyl ores phosphate 6% Acryloid HF 855 83%trioctyl phosphate 10% diphenyl cresyl phosphate. 5.9% Acryloid HF 8551% giycidyi phenyl ether .1% Wax disulfide 83% trioctyl phosphate 9.8%diphenyl cresyl phosphate 6% Acryloid HF 855 1% glycidyl phenyl ether0.2% PaSr reaction product of pinene.. 83% trioctyl phosphate 9.8%diphenyl cresyl phosphate 6% Acryloid HF 855 1% glycidyl phenyl ether0.2% suliurized sperm oil 100% diphenyl ethyl phosphate {98.9% diphenylethyl phosphate 1% glycidyl phenyi ether 0.1% wax disulfide {98.9%dipheny] ethyl phosphate.

1% zlycidyl phenyl ether 0.1% butyl disulfide 85% trioctyl phosphate 10%diphenyl cresyi phosphate 5% Acryloid HF 8125 84% trioctyl phosphate 10%diphenyl cresyl phosphate 5% Acryloid HF 8125 1% glycidyl pheuyl ethe84.7% trioctyl phosphate. 10% diphenyl cresyl phosphate. 5% Acryioid HF8125 3% P285 reaction product with pinene. 84% trioctyl phosphate 9.9%diphenyl cresyl phosphate. 5% Acryloid HF 8125 1% glycidyl pcnyl ether.0.1% wax disulfide 100% dioctyl phthalate. 98.9% dioctyl phthalate. 1%giycidyl phenyl ether- 0.1% wax disulfide sitions of this invention,each component 'of which may be used in amounts indicated above.

Components Present Phosphorus-Containing Compound:

tributyl phosphate 2; triamyl phosphate tri-2-ethy1hexy1 phosphatetri-n-octyl phosphate Composition No.

dibutyl octyl phosphate tri2-ethylbuty1 phosphatetris(3,5,5-trin1ethy1hexy1) phosphate tricresyl phosphatediphenyl cresylphosphate...

Composition No. Components Present I I 1 I I Phosphorus-Containing O o mp o u n d Continued tributyl phosphite x dioctyliso-octenylphosphonatcL. dioctyl styryl phosphonate tris-2-chloroethyl phosphate.tri-hutoxyethyl phosphate. tri-butoxyoctyl phosphate. di-butyl n-octanephosphon iris (trimethyl cyclohexyl carbinyl) phosphate .r x phosphateof 3-hydroxy-propyl ulfid dimethyltetradecanephosphonate. x ViscosityIndex Improving Agent:

Polyisobutene L. x x x x Polymerized ester of the ac lie acid series x xx x x Alkylated styrene polymer x rr. L. x Epoxy Compound:

glycidyl phenylcther x x x styrene oxide x glycidyl cyclohexyl ethglycidyl o-cresyl ether. glycidyl methyl ether glycidyl isopropy] ethcrisobutylene oxide butadiene monoxide glycidyl ethyl ether OrganicSulfur-containing Compound wax disulfide sulfurized sperm oil x P285reaction product with pinene di -benzyl disulfide di-octyldisulfide. r.x

I claim as my invention: phatic disulfldes, aromatic disul-fides,sulfurized 1. A hydraulic fluid composition com-prising a sperm oils,and sulfurized terpenes. major proportion of a dialkylarylphosphine 6. Ahydraulic fluid composition comprising a oxide, 0.25 to 5% by weight ofthe total compomajor proportion of diphenyl octyl phosphate, sition ofan epoxy compound and 0.025 to 1% 0.25 to 5% by weight of an. epoxycompound and by weight of the total composition of a sulfur- 0.025 to 1%by weight of the total composition containing organic compound selectedfrom the 40 of an oil-soluble.sulfur-containin organic com- O p ting ofalip at c disulfides, aromatic Pound selected from the group consistingof alidisulfldes, sulfurized sperm oils, and sulfurized phaticdisulfldes, aromatic disulfides, sulfurized terpenes. sperm oils, andsulfurized terpenes.

2. A hydraulic fluid composition comp n a 7. A hydraulic fluidcomposition comprising major proportion of a tria1ky1 phosphate, 0.25 to5 a major proportion of a mixtur of a trioctyl 5% by weight of the totalcomposition of an epoxy phosphate and diphenyl cresyl phosphate, 0.25compound and 0.025 to 1% by weight of the total to 5% by weight of thetotal composition of an composition of a sulfur-containing organiccomepoxy compound and 0.025170 1% by eight of. pound selected from thegroup consisting of alithe total composition of a sulfur-containingorphatic disulfldes, aromatic disulfides, sulfurized 5n ganic compoundselected from the group consistsperm oils, and sulfurized terpenes. ingof aliphatic disulfldes, aromatic disulfides, 3. A hydraulic fluidcomposition comprising a sulfurized sperm oils, and sulfurized terpenes.major proportion of triarylphosphate; 0.25 to 5% 8. A hydraulic fluidcomposition comprising by weight of the total composition. of an epoxyto 95% by weight of thetotal composition of dicompound and 0.025 to 1%by weight of the total phenyl ootyl phosphate, 0.25 to 5% b weight ofcomposition of a sulfur-containing organic. comthe total composition ofglycidyl phenyl ether and pound selected from the group consisting ofali- 0.05 to 0.2% by weight of the total composiphatic disulfldcs,aromatic disulfides, sulfurized. tion of wax disulfide.

sperm oils, and sulfurized terpenes. 9. A hydraulic fluid compositioncomprising a 4. A hydraulic fluid composition comprising a or majorproportion of an ester of an acid of phosmajor proportion of a mixedalkyl aryl phosphate, phorus,.0.25 to 5% by weight of the total composi-0.25 to 5% by weight of the total composition of tion of an epoxycompound and 0.025 to 1% by an epoxy compound and 0.025 to 1% by weightweight. of the total composition of a su1fur-c n of the totalcomposition of a sulfur-containing taining organic compound, organiccompound selected from the group con- 5 10. A composition comprising amajor proporsisting of aliphatic disulfides, aromatic disultion of atrialkyl p sphate, 0.25 to 5% by weight fldes, sulfurized sperm oils,and sulfurized terof the total composition of an aryl epoxy compenes. pu d a d to 1% by weight of the total 5. A hydraulic fluid compositioncomprising a composition ofan aliphatic disulfide. major proportion of amixture of trialkyl phoso 11. A composition comprising a majorproporphate and a tnaryl phosphate 0.25 to 5% by tion of a triarylphosphate, 0.25 to 5% by weight weightof the total composition of anepox comof the total composition of a glycidyl ether and pound and 0.025to 1% by weight of the total 0.025 to 1% by weight of the totalcomposition composition of a sulfur-containing organic comof an aromaticdisulfide.

pound selected from the group consisting of ali- 12-. A fluidcomposition comprising a major proportion of a diaryl alkyl phosphate,0.25 to 5% by weight of the total composition of aglycidyl ethercontaining one carbocylic group directly attached to the ether oxygenatom and 0.025 to 1% by weight of the total composition of a Waxdisulfide.

13.91 fluid composition comprising a major proportion of a dialkyl arylphosphine oxide, 0.25 to 5% by weight of the total composition of agiycidyl ether and 0.025 to 1% by Weight of the total composition of awax disulfide.

14. A composition comprising a major proportion of a phosphorus compoundof the group consisting of an ester of an acid of phosphorus andtrihydrocarbyl phosphine oxides, 0.25 to 5% by weight of the totalcomposition of an epoxy compound and 0.025 to 1% b weight of the totalcomposition of a sulfur-containing organic compound of the groupconsisting of aliphatic disulfides, aromatic disulfides, sulfurizedsperm oils, and sulfurized terpenes.

15. A hydraulic fluid composition comprising a major proportion ofdiphenyl octyl phosphate, 0.25% to 5% by weight or" a glycidyl ether and0.025% to 1% by Weight of wax disulfide.

16. A hydraulic fluid composition comprising a major proportion of amixture of a trioctyl phosphate and diphenyl cresyl phosphate, 0.25% to5% by weight of the total composition of an epoxy compound and 0.025% to1% by weight of the total composition of the wax disulfide.

17. A composition comprising a, major propor- 14 tion of an ester of anacid of phorphorus, 0.25-5% by weight of the total composition of anepoxy compound and 0.0251% by weight of the total composition of asulfur-containing organic compound.

18. A composition comprising a major proportion of an ester of aphosphorus acid and 025-5 by weight of glycidyl phenyl ether and 0.0251%by Weight of the total composition of an aliphatic disulfide.

19. A composition comprising a major proportion of an ester of aphosphorus acid and 0.25-5% by Weight of gly-cidyl phenyl ether and0.025-1% by weight of the total composition of a wax disulfide.

20. A composition comprising a major proportion of an ester of aphosphorus acid and 0.25-5% by weight of a glycidyl ether and 0.025-1%by weight of the total composition of a wax disulfide.

FORREST J. WATSON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,404,871 Vann Ess et a1 July 30, 1946 2,410,608 Morgan Nov.5, 1946 2,442,741 Morgan June 1, 1948 2,509,620 Watson et a1 May 30,1950 2,531,829 Seymour Nov. 28, 1950 2,549,270 \Vatson Apr. 1'7, 1951

1. A HYDRAULIC FLUID COMPOSITION COMPRISING A MAJOR PROPORTION OF ADIALKYLARYLPHOSPHINE OXIDE, 0.25 TO 5% BY WEIGHT OF THE TOTALCOMPOSISTION OF AN EPOXY COMPOUND AND 0.025 TO 1% BY WEIGHT OF THE TOTALCOMPOSITION OF A SULFURCONTAINING ORGANIC COMPOUND SELECTED FROM THEGROUP CONSISTING OF ALIPHATIC DISULFIDES, AROMATIC DISULFIDES,SULFIRIZED SPERM OILS, AND SULFURIZED TERPENES.